Fan housing



March 16, 1965 D. E. HARRIS 3,173,605

FAN HOUSING Filed June 21, 1963 iq. l.

INVENTOR.

MM 5 Wm w BY United States Patent 3,173,605 FAN HOUSING Dwight E. Harris, Woodstock, N.Y., assignor to Rotron Manufacturing Co., Inc., Woodstock, N.Y., a corporation of New York Filed June 21, 1963, Ser. No. 289,498 8 Claims. (Cl. 230-120) This invention relates in general to fans and more particularly to fans having a diverging throat.

Fans which have a diverging throat are generally employed where a relatively high pressure differential must be created. Typically the relatively high pressure differential is required to overcome the resistance created by a filter through which the air circulates. When cooling electronic equipment there is usually a filter between the fan and the equipment and, in addition, the equipment is inside a casing so that both the filter and the relative airtightness of the casing impose considerable resistance to the movement of air. To overcome this resistance the fan must build up a pressure differential considerably greater than that provided by the conventional straight throat fan. A preferred type of fan design to build up adequate pressure is one which has a diverging throat and in which there is relatively close tolerances between the ends of the fan blade and the peripheral throat surface.

The spokes of the housing around the fan blade should be located downstream in order to avoid creating turbulences in the air that impinges on the fan blades and thus to avoid noise and inefficiency. Since the throat periphery diverges in the direction of air movement through the throat, there results a total fan blade housing which makes it impossible to assemble the fan blades into the housing without building a two piece frame. In addition, close axial tolerances must be maintained on the positioning of the fan blades so that the fan blade itself will maintain the proper close clearance between the edges of the fan blade and the throat periphery formed by the inner wall of the housing within which the fan blade is located.

The two piece housing and the need for close fan blade tolerances impose added costs on the assembly of the fan.

Accordingly, it is a major purpose of this invention to simplify the assembly of a fan having a diverging throat.

It is another object of this invention to accommodate the various tolerances involved in the parts which make up the assembly of the fan.

It is a further object of this invention to permit a simple means for reducing the noise output of a fan which devel ops a relatively high static head.

It is a specific object of this invention to provide an insert for assembly with the main housing to provide the diverging inner wall of the housing.

Other objects and purposes of this invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing, in which:

FIG. 1 is a front elevation of the housing of this invention;

FIG 2 is a partial section along the plane 2-2 of FIG. 1;

FIG. 3 is a cross-section, of the inner wall insert, taken through a locking tab on the insert;

FIG. 4 is an elevation of a segment of the insert of FIG. 2;

FIG. 5 is a section along the inner surface of the fan frame showing the sockets adapted to engage the tabs on the insert; and

FIG. 6 is a section along 6-6 in FIG. 5; the section being taken through the assembled housing to show the engagement between frame sockets and insert tab.

FIG. 1 is a somewhat simplified illustration of a fan 10 embodying this invention. Fan blades 11 are mounted on a hub 12 to form what we might term the skeleton fan. Within the hub 12 there is located the motor which drives the fan blades 11. Around this skeleton fan composed of fan blades 11 and hub 12, there is positioned the housing 15. The housing 15 includes a hub cap 16 to which the hub 12 is journaled for rotation. From the hub cap 16 spokes 17 extend radially to support the peripheral shell 18 an insert 24. The inner wall 19 of the housing 15 diverges in the direction of air current flow except for the bell-shaped mouth portion 20.

The outer edges of the fan blades 11 closely conform to the diverging inner wall 19 with only enough clearance so that the fan blades are completely free to rotate. The area between the hub 12 and inner wall 19, within which the blades 11 are located, is the throat 21 of this fan 10.

The spokes 17 must be located downstream of the air flow through the throat 21 so as not to create turbulences in the air that impinges on the fan blade 11 and thus to avoid noise and inefficiency.

It is possible to mount the fan blades 11 in the throat 21 by having the spokes 17 removable from the rest of the housing 15. However, the cost of assembly would be greatly decreased if the housing 15 could be manufactored as a single unit. Accordingly, in this invention the housing 15 is made in two pieces as illustrated. The peripheral shell 18, spokes 17 and hub cap 16 are made as one integral unit called herein the frame. The second unit is an annular insert 24 having a wedge-shaped crosssection which is removably mounted on the inside of the peripheral shell 18 to form the diverging inner wall 19. The frame and the insert 24 together constitute the housing 15.

The insert 24 is made of a resilient plastic material, so as to be tough and springy. The material must be resilient such as is exemplified by any of the typical thermoplastic materials.

The insert 24 is snapped into the frame by means of projections 26 located on fingers 28, which fingers 28 form part of the outer surface of the insert 24. The exact arrangement of these projections 26 and fingers 28 can best be understood by reference to FIGS. 2 through 5. A cross-section of the insert 24 at the place where a finger 28 is located is shown in FIG. 2. As may be seen in FIG. 2, the finger 28 is formed by an undercutting near the outer surface 30 of the insert 24. The undercutting provides an area 29 beneath the finger and into which the finger 28 can be flexed so that the projection 26 can pass under the shell 18. Since the finger 28 must be free to flex, to side cuts 31 are required, as shown in FIG. 3. Two of these fingers 28, spaced apart together with outwardly extending projections 26, have been found to be adequate and preferable.

When the insert 24 is assembled into the frame, the fingers 28 are located near the inlet to the fan 10.

Matching sockets 33 for the projections 26 are provided in the inner wall 34 of the shell 18 near the inlet side of the housing 15. As the insert 24 is inserted into the 3 frame, the innerwal'l'sae'frne shell I8 will intercept the projections 26 and because of the curved leading surfaces 35 on the projections 26 will exert a radial pressure component which .will deflect the finger 28 inwardly until the projections 26 can pass under the shell 18. The insert 24 is then pushed and rotated under the shell 18 until the projections 26snap into place inside a socket 33,

by which means the insert 24 is held from further axial or angular displacement. The projections 26 are placed 180 apartand thus the sockets33 must be placed 180" apart so thatreachprojection 26 will beproperly received in a socket 33.

4 V formed by twoside cuts into saidoutersurface and an undercut area beneath said finger, whereby the outer'surface of said finger is a part of said outer surface .of said in- As nlay be seeninIFIGS. 4' and 5, a very use'fulvaria-- 7 "diameter of the sockets and thus related sockets 33 will have to'be angularly as well as axially displaced from one another. In one embodiment, the .fingers 28.. were designed to be of an inch in lengthand the projections 26. were designed to be modified squares having a diameter of approximately A; of an inch. Accordingly, the sockets 33had diameters of substantially of an inch. Sinceit was desired to provide for axial adjustments that were only .'040'inch*apart, it became necessary to include a inch radial separation between adjacent sockets 33..

Certain modifications-in the "above detailed. disclosure would be evident to one skilled in this art and it is to be understood that the invention .as claimed includes such variations and modifications.

For example, any number of. sockets 33 could be included in association with a single projection 26 to provide a greater number of adjustni'gsteps at any desired axial increment.

The undercut area 29 is illustrated as annular since it is easier to moldl the insert 24 in such'a fashion Obviously, the area 29 need only extend between sidecuts 31.

More broadly, insert material could beselected so that a it woul'dfibe possible to avoid having to provide for the required flexibility by means. of the undercut area and side cuts 31. There are potential insert materials whose compressibliity is such that the body of the insert could be solid and yet themateri'al would give 'enoughso-that a projection :26 could'be passed under theshell 18. What counts is that the projection 26 be resiliently mounted on the insert 24 so that the projection 26 canibe deflected on insertion of the insert "24 and 'will return'to its'original 1 position as 'it mates with a socket 33.

The sockets-33 and projection 26 might .well be reversed in location. In-such' a case,a=projection, comparable to rthe projection 26. illustrated, would project inwardly from the inner surfaceof the shell '18 and one or more sockets. 'would be molded into the upper surface of the insert 24 to receive the projection and provide the. desired remov- I able locking of insert 24 to shell 18'.

What is claimed is: l.' An annular fan housinginsert having aidiverging inher surface and'a right'circular cylindrical outer surface,

aresili'ent finger along said outer surface, said finger being formedby two side cuts intosa-id outersurface and' a'n undercut area beneath said finger, whereby the outer surface ofsaid finger is a part of said outer surface of said insert, saidfinger including a projection extending above said outer surface of said insert.

2. An annular fanhousing insert-having a diverging irrner surface anda right circularcylindrical outer surface, a resilient finger along said outer surface, said fingerbeing sert, said finger including a projection extending above the outer surface of said finger,'said finger terminating at the side, of said annular insert having the lesser inside diameter.

3. A diverging throat fan housing comprising: a frame having a shell with an inner surface, said inner surface being a first lockingsurface, and an insert having a diverging innersurface and an outer surface flush with said 'first lockingsurfaceof said shell, said diverging innersurface of said insert defin- -ing the periphery'of 'saiddiver'ging. throat,- said insert including a" finger along said outer surface of said insert, saidsfinger being formed by two side cuts into said outer surface of said insert and an nmdercut area beneath said finger, the outer surface of said finger being a second locking surface, f a projection extending from one of said locking surfaces, a matching socket in the. other one of said locking surfaces, whereby said finger may be'defiected by said projection to. permit manual insertionof said insert into said shell and whereby said'socket engages said projection to hold said insert in said frame against axial and angular displacement during operation of said fan.

4. A fan housing comprising: 7

a frame having a shell, and.

an inserthaving a diverging inner surface and an outer surface flush with theginner wall of said shell,

said insert includinga finger along said outer surface of said insert, said finger being formed by two side cuts into said outer surface of said insert and an undercut 'areab'eneath, said finger, said finger including a projection extending above the outer surface of said'finger,"

sa'id shell'includ-ing a'socket along its inner wall, said socket en'gaging said projection to :hold said insert in said frame against axial and angular displacement during oper'ation'o'f said fan. I a

5. fan housingj comprising:

a frame having a shell, and

an insert having a diverging. inner surface and an outer surface flush with the inner wall of said shell,

said insert including a finger along said outer surface of said insert, said finger beingforrned by two side cuts into said outer surfaceof said insert and an undercut areabeneath said'fingen: a

said finger including a projection extending above the outersurface'of said finger,

said shell including a plurality of axially displaced sockets along its inner wall, one of said sockets engaging said 'tab to hold said insert in said frame against axial and angular displacement during operation of said fan the other of said sockets permitting'adjustment of the axial position of said insert.

6.-An annular fan housing insert having-a diverging inner surface and a cylindrical outer surface, a resilient finger along said'outer surface, ,said finger being formed by two side cuts into said 'outer surface and an undercut area beneath said finger, whereby the outer surface of said finger is a part'of' said outer surface of said insert, said finger including plurality of'axially' displaced sockets along the outer surface ofsaid'finger.

7. A diverging throatfan-housing comprising:

5 a frame having a peripheral shell and a'front portion a resilient projection extending from one of said locking whereby said resilient projection may be mated with any one of said sockets to provide adjustment of the axial position of said insert and thereby obtain de sired clearance between the periphery of said diverg ing throat and the fan blades of whatever skeleton fan may be assembled in said housing.

A diverging throat fan comprising:

frame having a peripheral shell and a front portion including spokes, said spokes being integral With said peripheral shell, the inner surface of said peripheral shell being a first locking surface,

skeleton fan mounted in said frame and adapted to move air toward said spokes,

a peripheral removable insert having an inner surface whereby said resilient projection may be mated with any one of said sockets to provide adjustment of the axial position of said insert and thereby'obtain desired clearance between the periphery of said diverging throat and the fan blades of said skeleton fan.

References Cited in the file of this patent UNITED STATES PATENTS 1,867,809 Chase July 19, 1932 2,100,946 Mey Nov. 30, 1937 2,763,426 Erwin Sept. 18, 1956 2,861,829 Johanson et al Nov. 25, 1958 2,879,936 Faught Mar. 31, 1959 2,930,521 Koehring Mar. 29, 1960 2,982,586 Gliebe May 2, 1961 2,994,472 Botje Aug. 1, 1961 3,042,365 Curtis et al. July 3, 1962 3,068,016 Dega Dec. 11, 1962 FOREIGN PATENTS 975,879 France Oct. 17, 1950 441,706 Great Britain Jan. 24, 1936 791,568 Great Britain Mar. 5, 1958 313,026 Switzerland Apr. 30, 1956 

1. AN ANNULAR FAN HOUSING INSERT HAVING A DIVERGING INNER SURFACE AND A RIGHT CIRCULAR CYLINDRICAL OUTER SURFACE, A RESILIENT FINGER ALONG SAID OUTER SURFACE, SAID FINGER BEING FORMED BY TWO SIDE CUTS INTO SAID OUTER SURFACE AND AN UNDERCUT AREA BENEATH SAID FINGER, WHEREBY THE OUTER SURFACE OF SAID FINGER IS A PART OF SAID OUTER SURFACE OF SAID INSERT, SAID FINGER INCLUDING A PROJECTION EXTENDING ABOVE SAID OUTER SURFACE OF SAID INSERT. 